In some submarine research programs, it is desired to make an instrumented capsule descend at very high speed into the deep sea, for example down to 1000 to 2000 m.
When the capsule is fixed on a capstan on board of a ship, the obtained speed is insufficient in view of the fact that the capstan must bear a cable which is 1000 to 2000 m long. The speeds which can thus be realised do not exceed some meters per second. Another solution would be to allow the capsule to fall along a guiding cable by gravity and to provide for braking of the capsule at the end of travel. However, this braking device must be well adjusted for ensuring a controlled deceleration of the capsule, because otherwise the impact transmitted on the cable during an abrupt braking might lead to the rupture of the cable or the destruction of the measuring instruments.
The invention thus aims at presenting a braking device according to the preamble of claim 1, which permits a fine calibration of the capsule deceleration and thus reduces the danger of cable rupture while authorizing a very high descending speed close to that of the free fall.